Cylinder assemblies which activate the bolt or latch of a lock are well-known and have been used in known manner in a wide variety of locking mechanisms such as mortise locks, rim locks and in key-in-knob type locks in which the cylinder assembly is mounted in the door knob. Key-in-knob type locks are commonly called cylindrical locksets which are generally mounted in a circular hole in a door. The cylinder assembly of cylindrical locksets is also used in conventional manner in patio doors, or to activate dead bolts and padlocks which do not include the entire lockset assembly.
The cylinder assembly comprises an exterior body of desired configuration and a cylindrical plug. The body and plug have aligned holes which carry spring biased slidable pins that are released by inserting a key into the plug which is thereupon free to turn some form of camming means for retracting the bolt, dead bolt, latch or padlock locking mechanism to release the type of lock at hand.
One drawback to the known assemblies is that the cylindrical plugs cannot be freely interchanged and if there is a desire to change the plug of one manufacturer for that of another, the entire cylinder assembly has to be replaced. Furthermore, it frequently happens that a cylinder assembly designed for a mortise lock cannot be used in a rim lock.